The replacement of a conveyor roller is a difficult task in that the conveyor belts that need to be lifted off of rollers are usually troughed and tensioned and may be quite wide, for example 60 inches in width, and may also be on an incline. For this purpose, a belt lifter often has to be placed on the supporting frame for the conveyor within a confined space. While current belt lifters lift the belt as much as ten inches, it would be desirable to lift the belt higher than ten inches to provide adequate space for easy removal of a conveyor belt roller, for instance. Because the conveyor belt lifters are used in the field for relatively large troughed, conveyor belts, although the lifter also could be used for non-troughed conveyor belts, the lifter has to be easily portable and preferably light weight so that it can be carried to the place of roller replacement or where it is desired to create a splicing station for a repair of a belt rip or to provide a splice for the belt. A splicing station is usually created by lifting the belt until it is flat with the trough removed; and then a piece of plywood is slipped under the belt between the belt and rollers or the belt lifter to create a splicing station.
The belt lifter should be safe and stable for commercial usage in that it should resist toppling or rolling over, and the belt lifter needs to be easily centered and operated. One commercially marketed conveyor belt lifter is able to lift about 880 kilograms or roughly 2300 pounds; however, it would be desirable to provide even greater lifting force. One belt lifter manufacturer provides two different sizes of belt lifters with the heavier or larger size providing the 2300 pounds of lifting force and approximately 10 inches of vertical travel or lift height for the belt. Another manufacturer provides a lift capacity of about 1000 kilograms and provides approximately 10 inches of vertical lift. Providing additional vertical lift is difficult in that the belt tension and therefore the downward force exerted on the belt lifter increases substantially for each inch beyond the current 10 inch lift provided by commercial belt lifters. That is, the belt lifter is working against increased downward loading from the tensioned belt as the belt continues to be raised vertically higher. Therefore, especially with wider belts it may be important that the belt lifter be stabilized and the belt engaging member be raised parallel with the support substantially centered under such high lift loads.
One of the commercially available belt lifters is disclosed in Australian Patent Number 580705. As described in this patent, the lift is by a scissors-like jack mechanism which provides a mechanical advantage to provide the lifting force, but additionally has a stabilizing linkage assembly which insures that the belt engaging member is lifted parallel to the base support particularly if the load on the conveyor is somewhat off center. Preferably, the belt lifter is not only stable and provides a parallel lift capacity but it is also light-weight, stable, and has a low profile, for example seven inches or less, so that it can be fit into a confined space under the conveyor belt.